Miniature bearings are sometimes referred to as instrument bearings or micro bearings.Miniature Ball bearings are machined components that include an outer ring, inner ring, balls, retainers, shields and snap rings. Our miniature ball bearings are available in inch and metric sizes, open or shielded and flanged or unflanged. Miniature ball bearings are useful in a wide variety of applications. Bearings. The two most common types of bearings are plain bearings and rolling bearings